Colored glass



Patented Oct. 3, 1939 UNITED STATES PATENT OFFICE COLORED GLASS DelawareNo Drawing. Application December 15, 1937, Serial No. 179,866

9 Claims.

This invention relates to the production of ruby glass and moreparticularly to the production of copper ruby glass.

Copper ruby glass, 1. e. ruby or red glass pro duced by the addition ofa copper compound or copper to the glass batch, has been producedheretofore by fusion of the glass batch under carefully controlledconditions. Thus, so far as we are aware, it has been necessary in priormethods to effect fusion in closed pots in order to protect the contentsof the pot from the furnace atmosphere. One disadvantage of such amethod is that transfer of heat to the pot contents is ineilicient, thetransfer being entirely 16 through the pot walls or cover. Even underthese conditions, control of color intensity in the final ware has beendiflicult and in general unreliable.

It is an object of our invention to provide an 20 improved method forpreparing copper ruby glass wherein the above disadvantages of themethods heretofore employed are overcome to a large extent or entirelyeliminated. A further object is the provision of an improved methodwherein fusion may be carried out in open pots or tanks under heatingconditions which need not be carefully controlled. A particular objectis to provide an improved method for preparing copper ruby glass whichpermits of more effective 30 and reliable control of the intensity ofcolor in the final ware than has been possible by methods practicedheretofore. A still further object is to provide improved additionagents for glass batches which are to be used in the production ofcopper ruby glass. These and other objects will be apparent from theensuing description of our invention.

The above objects may be accomplished in accordance with our inventionby adding a suitable 40 cyanogen compound to a glass batch whichcontains, in addition to the usual batch ingredients, a copper compoundand thereafter fusing the resulting mix. Suitable cyanogen compounds forthe present purpose are the metal cyanides, in-

45 cluding the simple and complex metal cyanides, metal cyanates andmetal cyanamides. Of course, the metal cyanides and particularly thealkali metal cyanides, e. g. sodium cyanide, are preferred.

We have discovered that the use of these cyanogen compounds eifects thedevelopment of color uniformly throughout the resulting ware,

facilitates the control of color intensity in the were and obviates thenecessity of carrying out 55 the fusion operation under carefullycontrolled conditions, e. g. in closed pots. The use of open pots ortanks results in recognized advantages among which is a more efficienttransfer of heat to the batch being fused since flame and radiant heatis applied directly to the surface of the 5 batch. Furthermore, carefulcontrol of the flame as regards its reducing or oxidizing character isnot necessary when practicing our invention even though the melt isdirectly exposed to the flame as, for example, in an open pot or 10tank. It is thus apparent that our method involving the use of the abovecyanogen compounds overcomes many of the important disadvantagescharacteristic of earlier methods and that it is well suited forcommercial operation.

The intensity of the red color in the ruby glass produced by the presentmethod may vary depending upon various factors which are discussedbelow. It is therefore to be understood that our invention is notrestricted to the production of red or ruby glass of a specific range ofcolor intensity but covers any copper ruby glass, i. e. any red glassproduced by the use in a glass batch of a copper compound or mixture ofsuch compounds in conjunction with one or more of the above cyanogencompounds.

The following examples illustrate the production of ruby glass inaccordance with our invention:

Example 1 A glass batch is prepared containing the followingingredients:

Parts by weight Sand 110 Potassium carbonate 10 Sodium carbonate '40Calcium oxide 13 Aluminum oxide 3.5 Cuprous oxide 0.25 Stannous oxide0.32 40 Sodium cyanide 1.25

Example 2 A similar ruby glass is obtained by substituting cuprouscyanide in place of cuprous oxide inthe glass batch given in Example 1.'In this case, less sodium cyanide need be used since the cuprouscyanide serves as part of the addition agent as well as the source ofcopper.

Metal cyanates or cyanamides may be used with good results in place oithe sodium cyanide in Example 1 although the metal cyanides,particularly the alkali metal cyanides. are some- -Any of the usualcopper ruby glass formulae may be employed with excellent results. Ingeneral, however, the presence of calcium oxide and aluminum oxide inthe batch is desired in that these substances tend to improve the colorof the final product. The presence of stannous oxide, although notessential, is generally desirable in that it improves the color strikingproperty of the glass. Aluminum oxide also causes the color to strikemore readily and this efiect appears to increase somewhat as theproportion of aluminum oxide is increased. However, the amounts of theseconstituents may vary within wide limits and the optimum amounts for agiven batch may be readily determined by any skilled glass maker.

An important advantage resulting from the use of our cyanogen compoundsin the production of copper ruby glass is that such use makes possiblean effective method for controlling the intensity of color in the finalproduct. Control of color intensity in copper ruby glass has always beena difilcult problem with the art. However, by employing our improvedaddition agents and especially by adjusting the amounts of both thecopper compound and the cyanogen compound in the batch, the colorintensity may be controlled have discovered that adjustment of theamount of copper compound may be supplemented effectively by adjustingthe amount of cyanogen compound employed. In general, ware having agiven color intensitymay be produced using a relatively large or smallamount of copper compound, e. g. cuprous oxide, provided the properamount of cyanogen compound is employed in conjunction therewith. Thus,a relatively small amount of cuprous oxide in conjunction with arelatively large amount of sodium cyanide may be used to givesubstantially the same color intensity as may be obtained with acomparatively large amount of cuprous oxide and a comparatively smallamount of sodium cyanide. It is therefore apparent that adjustment ofthe amount of sodium cyanide greatly facilitates the control of colorintensity by varying the amount of copper compound.

The particular cyanogen compound or mixture of such. compounds that isbest employed in a glass batch will depend upon the other batchingredients as well as upon the color requirements of the desired ware.The alkali metal cyanides, e. g. sodium cyanide, are generally suitablefor use in any copper ruby glass batch and their use is generallypreferred in that it does not involve the introduction of metallicconstituents which impart color to the glass. However, the use ofcyanogen compounds which introduce metals imparting color is notnecessarily objectionable and parts of sand, may generally be usedwithout may frequentlybe desirable in that glass having a modified rubycolor may be obtained as a result of. such use. Thus, although iron andco.-

balt compounds impart'color'to glass, cyanogen compounds, e. g. complexmetal cyanides, of these metals may-be used in controlled amounts eitheralone or in combination with alkali metal cyanides as addition agents inaccordance with our invention to produce glassfhaving a. modified rubycolor. The eilfect of such metals-in the glass may be to mask anundesirable colornormally present or to produce a blended'color.

No satisfactory explanation is apparent as to how our cyanogen compoundsfunction to pro-' duce the beneficial results attending their use. Thesuggestion that they function as reducing agents is not entirelysatisfactory in that it does not explain their beneficial action inaccelerating the development .of color and in their action in varyingthe intensity of color when varying amounts are employed in conjunctionwith a given amount of copper compound. A correct explanation of theirmode of action would undoubtedly involve manyiactors whose importance 1and relationships to each other are not apparent. It may be-definitelysaid, however, that the beneficial results accruing from the use ofthese compounds in accordance with our invention are due in large partto the fact that these compounds, 1. e. metal cyanides, cyanates andcyanamides, dissolve readily during the fusion treatment so that theirbeneficial action is exerted uniformly throughout the melt. 1

Because the present cyanogen compounds are readily soluble in the glassmelt, they may be added if desired to the melt instead of to the batchprior to the fusion operation. However. we have found it generally to bemore convenient to add the material directly to the glass batch asillustrated in the above examples.

Our invention is not limited to the use of any specific amount of thecyanogen compound in the glass batch. The optimum amount for a givenbatch will depend in part upon the particular ingredients, e. g., thecopper compound and the cyanogen compound employed, the intensity ofcolor desired in the final product and also to some extent upon theconditions under which the glass batch is fused. In addition, it willalso depend upon the general ingredients of the glass batch. As has beenpointed out above, ingredients such as calcium oxide, aluminum oxide andstannous oxide tend to modify somewhat the final color as well as alsotoaiiect somewhat the rate of color development. It may be said, however,that an amount not exceeding about 1 to 2 parts 'per parts of sand issuiiicient to produce generally satisfactory results, although largeramounts, e. g. amounts equal to 5 to 1 parts by weight of the batch, maybe used in specific cases.

The desired final ratio of basic to acidic constituents of the glassshould be considered inn connection with the amount of cyanogen compoundto be used. When relatively large amounts of cyanogen compound areemployed, e. g. amounts equal to from 5 to 10% of the weight of thebatch, it may be necessary to increase the acidic ingredients, e. g.sand, of the batch in order to insure the desired ratio of basic toacidic constituents of the final glass. Relatively small amounts, e. g.1 to 2 parts per 100 correspondingly adjusting the ratio of basic toacidic ingredients; however, such adjustment may be made if desired.

While the use of the above cyanogen compounds renders the melt lesssensitive to the furnace atmosphere, it is generally necessary to employan amount of cyanogen compound corresponding somewhat to the oxidizingstrength of the furnace atmosphere. Thus, with a strongly oxidizingatmosphere, a relatively large amount of cyanogen compound is generallyrequired. The beneficial effects of the cyanogen compound in the meltis, however, exerted over a prolonged period of time, e. g. for 1 to 2days, so that relatively small amounts, e. g. 1 to 2 parts per 100 partsof sand, are generally suflicient even though the furnace atmosphere isslightly oxidizlng.

Our invention is not restricted to the use of any specific amount ofcopper compound in the batch since the amount will necessarily varyconsiderably depending upon the particular compound used and also uponthe intensity of color desired. There is usually no advantage in usingmore than, for example, about 0.5 part of cuprous oxide per 100 parts ofsand and about 0.2 to 0.25 part gives generally satisfactory results.However, as little as 0.02 part of cuprous oxide may be used inconjunction with, for example, sodium cyanide to produce ware having agood ruby color. Copper compounds other than cuprous oxide, e. g. coppersalts such as the carbonate, sulfate, chloride and the like, may be usedalthough the oxide is preferred for reasons of economy.

We have described our invention in connection with the production ofruby glass of the type illustrated. However, our. invention may bepracticed to produce' glasses of other types, for example, glasses whichare relatively high in acidic constituents. It is to be understood thatthe descriptions, procedural details and examples given above areintended to be illustrative and not restrictive of our invention. The

invention is to be limited only by the scope of the appended claims.

We claim:

1. A method for preparing ruby glass which comprises preparing a glassmelt which contains a copper compound and a metallic cyanogen compoundselected from the group consisting of metal cyanides, cyanates andcyanamides.

2. A process for preparing ruby glass comprising preparing a glass batchwhich includes as ingredients thereof a copper compound and a metalliccyanogen compound selected from the group consisting of metal cyanides,cyanates and cyanamides, and fusing said batch.

3. A process for preparing ruby glass comprising preparing a glass batchwhich includes as ingredients thereof a copper compound and an alkalimetal cyanide, and fusing said batch.

4. A process for preparing ruby glass comprising preparing a glass batchwhich includes as ingredients thereof a copper compound and sodiumcyanide, and fusing said batch.

5. A process for preparing ruby glass comprising adding copper cyanideto a glass batch and fusing the resulting mix.

' 6. A glass batch for the production of copper ruby glass containing asingredients thereof a copper compound and a metallic cyanogen compoundselected from the group consisting of metal cyanides, cyanates andcyanamides.

7. A glass batch for the production of copper ruby glass containing asingredients thereof a copper compound and an alkali metal cyanide.

8. A glass batch for the production of copper ruby glass containing asingredients thereof a. copper compound and sodium cyanide.

9. A glass batch for the production of copper ruby glass containingcopper cyanide as an ingredient thereof.

mm J. nonaovomw.

JOHN M. YOUEL. HAROLD E. KLEIN.

